Sheldon signed on to a letter this week as RNC chair Reince Priebus leads the GOP’s spring convention at the Lowe’s Hotel in Hollywood. The letter comes as some key party leaders, including Ohio U.S. Senator Rob Portman, express a softening of their past views on key social issues like gay marriage.

NBC News reported the letter from 13 conservative leaders warned Priebus and the GOP that “an abandonment of its principles will necessarily result in the abandonment of our constituents to their support.”

NBC said the the letter demands passage of a resolution at the RNC meeting “re-affirming the party’s 2012 national platform, which includes language calling for bans on abortion and same-sex marriage.”

Priebus’ Growth and Opportunity Project report, an effort to examine new paths forward for the GOP after 2012 election losses, aims to provide the party with possible ways to broaden its diversity and appeal to voters. Among the suggestions were to soften the tone on social issues such a abortion, reproductive rights and gay rights, all of which may be significant to younger voters.

But that’s not playing well with the social conservatives like Sheldon who wrote Priebus this week.

According to their letter reported by NBC:“It is the faith-based community which offers Republicans their best hope of expanding their support in these groups…Going ‘vanilla’ or even changing long held positions would quickly end this opportunity.”

More:“The fact that the party is strongly committed to traditional marriage has not prevented their involvement through GOProud or Log Cabin Republicans…We deeply resent the insinuation that we have treated homosexuals unkindly personally.”